JPH01136712A - Determination of quality of injection-molded object - Google Patents

Abstract

PURPOSE:To improve the accuracy in determination of quality in shape of an injection-molded object, by detecting simultaneously the temperature and pressure of resin filled in a cavity in an arbitrary defined time period as a function of time and comparing them with corresponding standard values. CONSTITUTION:A temperature sensor 18 detects the temperature T of a mold in an arbitrarily defined time period within the time elapsing since the beginning of a pressure dwell process. Similarly, the pressure P of the resin in a cavity 11 is detected by a pressure sensor 16. In the arithmetically processed value from T and P; T/P or P/T, T.P, (T+P) or (T+ or -P), assumed to be A, a function of time, A=f(t) is calculated in a processing section 19. By comparing this calculated value with the shot Ao=f(t), (the reference value) set up in advance in a set-up section 21 when a superior object was obtained, by a comparing section 20, the quality in the shape of the molded object is accurately determined.

Description

[Detailed description of the invention] Industrial application fields> The present invention relates to determining the quality of molded products of injection molding machines.

In particular, it relates to a method for determining the accuracy of shape and dimensions.

Conventionally, when determining the quality of the shape of a molded product in an injection molding machine, the resin pressure in the cavity and the injection pressure are measured over the elapsed time in the pressure holding process.

By finding it as a function of time P = f (t) and comparing it with the resin pressure, etc., P, = f (t) when a good product is obtained.

Alternatively, the quality of the molded product has been determined by comparing the mold temperature T = f (t) with the mold temperature T, = f (t) when a non-defective product is obtained.

<Problem to be solved by the invention> The resin in the cavity has the equation of state pv=a'r, (p
: pressure, v: volume, T: temperature, R: constant). Therefore, as in the past, only pressure T or temperature T was measured and two quality judgments were made.
It was impossible to determine the volume V.

An object of the present invention is to provide a method for accurately determining the shape of a molded product by determining its pressure and temperature, and determining the quality of the shape of a molded product.

Means to solve problems〉 SUMMARY OF THE INVENTION In order to achieve the above-mentioned objects.

Measure the mold temperature T and the resin pressure P in the cavity in an arbitrarily determined period of time that has elapsed since the start of the pressure holding process, and calculate the number of calculations for T and P, 7 or P, ff.
When A is J, T-P, (T+P) or (T-1=P), find the time function A = f (t), and use Ao = f (t) as the standard when a good product is obtained. ,
This is a method for determining the quality of an injection molded product, which is characterized in that the quality of the injection molded product is determined by comparing An = f (t).

Function: It is now possible to grasp the pressure and temperature during the pressure-holding process, and it has become possible to accurately judge whether the shape is good or bad.

<Example> Next, an example of the present invention will be described with reference to FIGS. 1 and 2. A mold 10 forms a cavity 11.

Reference numeral 12 denotes a barrel into which a screw 13 is inserted so as to be rotatable and movable forward and backward. Therefore, the raw resin supplied from the hopper 14 is heated by a heating device (not shown) provided on the outer diameter surface of the barrel 12, and as it is moved forward by the screw 13 (leftward in the figure), it is When the measured value reaches a preset value, the screw 13 moves forward from the retraction limit and is injected into the cavity 11. 15 extrusion pins/pressure sensor 16
is attached so that the resin pressure inside the cavity 11 can be detected. 17 is an extrusion bottle with a temperature sensor 1 at the tip.
8 is attached, and the temperature of the resin inside the cavity 11 can be detected. 19 is an arithmetic unit which calculates the pressure and temperature detected by the pressure sensor 16 and temperature sensor 18 in an arbitrary time period t1 set in the time setting unit 23 as a function of time, and sets the pressure and temperature in the setting unit 21 by the comparison unit 20. The value in the time period t1 set in the time setting device 23 at the time of molding a non-defective product is compared. 22 is a tolerance value setter for the arbitrarily set time period 1.
．． As shown in FIG. 2, the allowable value to be added to the results compared by the comparing section 20 is set in the arbitrarily set time period 1 during molding of non-defective products. An example in which the tolerance value ±Δ·T/P is added to the reference value diagram 24 in the upper limit value diagram 25. If the actual shot value diagram 29 shown by dotted lines as in the lower limit value diagram 26 deviates from the upper and lower limit value diagrams 25 and 26, the comparator 27 detects this and issues an alarm 28. You can also do that.

In the above embodiment, the temperature is the temperature of the resin in the mold cavity, and the pressure is the temperature of the resin in the cavity. Injection cylinder pressure, resin pressure in the barrel and nozzle may be used.

<Effects of the Invention> According to the present invention, since the temperature and pressure of the resin filled in the cavity can be detected simultaneously as a function of time, the volume, that is, the quality of the shape can be accurately determined.

[Brief explanation of the drawing]

FIGS. 1 and 2 are diagrams showing one embodiment of the present invention. FIG. 1 is a configuration diagram thereof, and FIG. 2 is a diagram showing an example of quality determination. 10... Mold, 11... Cavity, 16... Pressure sensor. 18... Temperature sensor, 19... Arithmetic unit, 20...
Comparison section, 21... Setting section, 22... Tolerance value setter,
23...Time setting device, 24...Reference value diagram, 25.
... Upper limit value diagram, 26... Lower limit value diagram. 27... Comparator, 28... Alarm, 29... Actual shot value diagram.

Claims (1)

[Claims] 1) The mold temperature T and the resin pressure P in the cavity are each measured in an arbitrarily determined time period during the time elapsed from the start of the pressure holding process, and the number of calculations for T and P is calculated. When T/P or P/T, T・P, (T+P) or (T±P) is A, calculate the time function A=f(t) and find the shot where a good product was obtained Ao=f(t) is the standard, and other shots An=
A method for determining the quality of an injection molded product, characterized in that the quality of the injection molded product is determined by comparing f(t). 2) The method for determining the quality of an injection molded product according to claim 1, wherein the mold temperature T is the resin temperature T in the cavity. 3) The method for determining the quality of an injection molded product according to claim 1, wherein the mold temperature T is the resin temperature in the barrel and nozzle of the injection molding machine. 4) The method for determining the quality of an injection molded product according to claim 1, wherein the mold temperature T is a barrel and nozzle temperature of an injection molding machine. 5) The method for determining the quality of injection molded products according to claims 1 to 4, wherein the resin pressure P in the cavity is the resin pressure in the barrel and nozzle of an injection molding machine. 6) A method for determining the quality of an injection molded product according to claims 1 to 4, wherein the resin pressure in the cavity is the oil pressure of an injection hydraulic cylinder of an injection molding machine.